package cn.edu.whu.MVCByHand.servlet;

import cn.edu.whu.MVCByHand.annotation.MyAutowired;
import cn.edu.whu.MVCByHand.annotation.MyService;
import cn.edu.whu.MVCByHand.annotation.MyController;
import cn.edu.whu.MVCByHand.annotation.MyRequestMapping;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.net.URL;
import java.util.*;
import java.util.logging.Logger;

public class MyDispatcherServlet extends HttpServlet {

	private Logger log=Logger.getLogger("init");

	private Properties properties = new Properties();

	private List<String> classNames = new ArrayList<>();

	private Map<String, Object> ioc = new HashMap<>();
	//handlerMapping的类型可以自定义为Handler
	private Map<String, Method> handlerMapping = new  HashMap<>();

	private Map<String, Object> controllerMap  =new HashMap<>();

	@Override
	public void init(ServletConfig config) throws ServletException {
		super.init();
		log.info("初始化MyDispatcherServlet");
		//1.加载配置文件，填充properties字段；
		doLoadConfig(config.getInitParameter("contextConfigLocation"));

		//2.根据properties，初始化所有相关联的类,扫描用户设定的包下面所有的类
		doScanner(properties.getProperty("scanPackage"));

		//3.拿到扫描到的类,通过反射机制,实例化,并且放到ioc容器中(k-v  beanName-bean) beanName默认是首字母小写
		doInstance();

		// 4.自动化注入依赖
		doAutowired();

		//5.初始化HandlerMapping(将url和method对应上)
		initHandlerMapping();

		doAutowired2();
	}

	@Override
	protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		// 注释掉父类实现，不然会报错：405 HTTP method GET is not supported by this URL
		//super.doPost(req, resp);
		log.info("执行MyDispatcherServlet的doPost()");
		try {
			//处理请求
			doDispatch(req,resp);
		} catch (Exception e) {
			resp.getWriter().write("500!! Server Exception");
		}
	}

	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		// 注释掉父类实现，不然会报错：405 HTTP method GET is not supported by this URL
		//super.doGet(req, resp);
		log.info("执行MyDispatcherServlet的doGet()");
		try {
			//处理请求
			doDispatch(req,resp);
		} catch (Exception e) {
			resp.getWriter().write("500!! Server Exception");
		}
	}

	private void doDispatch(HttpServletRequest req, HttpServletResponse resp) throws Exception {
		if(handlerMapping.isEmpty()){
			return;
		}
		String url =req.getRequestURI();
		String contextPath = req.getContextPath();
		url=url.replace(contextPath, "").replaceAll("/+", "/");
		// 去掉url前面的斜杠"/"，所有的@MyRequestMapping可以不用写斜杠"/"
		if(url.lastIndexOf('/')!=0){
			url=url.substring(1);
		}
		if(!this.handlerMapping.containsKey(url)){
			resp.getWriter().write("404 NOT FOUND!");
			log.info("404 NOT FOUND!");
			return;
		}
		Method method =this.handlerMapping.get(url);
		//获取方法的参数列表
		Class<?>[] parameterTypes = method.getParameterTypes();

		//获取请求的参数
		Map<String, String[]> parameterMap = req.getParameterMap();
		//保存参数值
		Object [] paramValues= new Object[parameterTypes.length];
		//方法的参数列表
		for (int i = 0; i<parameterTypes.length; i++){
			//根据参数名称，做某些处理
			String requestParam = parameterTypes[i].getSimpleName();
			if (requestParam.equals("HttpServletRequest")){
				//参数类型已明确，这边强转类型
				paramValues[i]=req;
				continue;
			}
			if (requestParam.equals("HttpServletResponse")){
				paramValues[i]=resp;
				continue;
			}
			if(requestParam.equals("String")){
				for (Map.Entry<String, String[]> param : parameterMap.entrySet()) {
					String value =Arrays.toString(param.getValue()).replaceAll("\\[|\\]", "").replaceAll(",\\s", ",");
					paramValues[i]=value;
				}
			}
		}
		//利用反射机制来调用
		try {
			//第一个参数是method所对应的实例 在ioc容器中
			//method.invoke(this.controllerMap.get(url), paramValues);
			method.invoke(this.controllerMap.get(url), paramValues);
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	/**
	 * Description:  根据配置文件位置，读取配置文件中的配置信息，将其填充到properties字段
	 * Params:
	 * @param location: 配置文件的位置
	 * return: void
	 * Author: CXJ
	 * Date: 2018/6/16 19:07
	 */
	private void  doLoadConfig(String location){

		//把web.xml中的contextConfigLocation对应value值的文件加载到流里面
		URL resource = this.getClass().getClassLoader().getResource(location);
		InputStream resourceAsStream = this.getClass().getClassLoader().getResourceAsStream(location);
		try {
			//用Properties文件加载文件里的内容
			log.info("读取"+location+"里面的文件");
			properties.load(resourceAsStream);
		} catch (IOException e) {
			e.printStackTrace();
		}finally {
			//关流
			if(null!=resourceAsStream){
				try {
					resourceAsStream.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
		}

	}

	/**
	 * Description:  将指定包下扫描得到的类，添加到classNames字段中；
	 * Params:
	 * @param packageName: 需要扫描的包名
	 * return: void
	 * Author: CXJ
	 * Date: 2018/6/16 19:05
	 */
	private void doScanner(String packageName) {

		URL url  =this.getClass().getClassLoader().getResource(""+packageName.replaceAll("\\.", "/"));
		File dir = new File(url.getFile());
		for (File file : dir.listFiles()) {
			if(file.isDirectory()){
				//递归读取包
				doScanner(packageName+"."+file.getName());
			}else{
				String className =packageName +"." +file.getName().replace(".class", "");
				classNames.add(className);
			}
		}
	}

	/**
	 * Description:  将classNames中的类实例化，经key-value：类名（小写）-类对象放入ioc字段中
	 * Params:
	 * @param :
	 * return: void
	 * Author: CXJ
	 * Date: 2018/6/16 19:09
	 */
	private void doInstance() {

		if (classNames.isEmpty()) {
			return;
		}
		for (String className : classNames) {
			try {
				//把类搞出来,反射来实例化(只有加@MyController需要实例化)
 				Class<?> clazz =Class.forName(className);
				if(clazz.isAnnotationPresent(MyController.class)){
					ioc.put(toLowerFirstWord(clazz.getSimpleName()),clazz.newInstance());
				}else if(clazz.isAnnotationPresent(MyService.class)){
					MyService myService=clazz.getAnnotation(MyService.class);
					String beanName=myService.value();
					if ("".equals(beanName.trim())){
						beanName=toLowerFirstWord(clazz.getSimpleName());
					}

					Object instance= clazz.newInstance();
					ioc.put(beanName,instance);
					Class[] interfaces=clazz.getInterfaces();
					for (Class<?> i:interfaces){
						ioc.put(i.getName(),instance);
					}
				}
				else{
					continue;
				}
			} catch (Exception e) {
				e.printStackTrace();
				continue;
			}
		}
	}

	/**
	 * Description:自动化的依赖注入
	 * Params:
	 * @param :
	 * return: void
	 * Author: CXJ
	 * Date: 2018/6/16 20:40
	 */
	private void doAutowired(){

		if (ioc.isEmpty()){
			return;
		}
		for (Map.Entry<String,Object> entry:ioc.entrySet()){
			//包括私有的方法，在spring中没有隐私，@MyAutowired可以注入public、private字段
			Field[] fields=entry.getValue().getClass().getDeclaredFields();
			for (Field field:fields){
				if (!field.isAnnotationPresent(MyAutowired.class)){
					continue;
				}
				MyAutowired autowired= field.getAnnotation(MyAutowired.class);
				String beanName=autowired.value().trim();
				if ("".equals(beanName)){
					beanName=field.getType().getName();
				}
				field.setAccessible(true);
				try {
					field.set(entry.getValue(),ioc.get(beanName));
				}catch (Exception e){
					e.printStackTrace();
					continue;
				}

			}
		}
	}

	private void doAutowired2(){

		if (controllerMap.isEmpty()){
			return;
		}
		for (Map.Entry<String,Object> entry:controllerMap.entrySet()){
			//包括私有的方法，在spring中没有隐私，@MyAutowired可以注入public、private字段
			Field[] fields=entry.getValue().getClass().getDeclaredFields();
			for (Field field:fields){
				if (!field.isAnnotationPresent(MyAutowired.class)){
					continue;
				}
				MyAutowired autowired= field.getAnnotation(MyAutowired.class);
				String beanName=autowired.value().trim();
				if ("".equals(beanName)){
					beanName=field.getType().getName();
				}
				field.setAccessible(true);
				try {
					field.set(entry.getValue(),ioc.get(beanName));
				}catch (Exception e){
					e.printStackTrace();
					continue;
				}

			}
		}
	}

	/**
	 * Description:  初始化HandlerMapping(将url和method对应上)
	 * Params:
	 * @param :
	 * return: void
	 * Author: CXJ
	 * Date: 2018/6/16 19:12
	 */
	private void initHandlerMapping(){

		if(ioc.isEmpty()){
			return;
		}
		try {
			for (Map.Entry<String, Object> entry: ioc.entrySet()) {
				Class<? extends Object> clazz = entry.getValue().getClass();
				if(!clazz.isAnnotationPresent(MyController.class)){
					continue;
				}

				//拼url时,是controller头的url拼上方法上的url
				String baseUrl ="";
				if(clazz.isAnnotationPresent(MyRequestMapping.class)){
					MyRequestMapping annotation = clazz.getAnnotation(MyRequestMapping.class);
					baseUrl=annotation.value();
				}
				Method[] methods = clazz.getMethods();
				for (Method method : methods) {
					if(!method.isAnnotationPresent(MyRequestMapping.class)){
						continue;
					}
					MyRequestMapping annotation = method.getAnnotation(MyRequestMapping.class);
					String url = annotation.value();

					url =(baseUrl+"/"+url).replaceAll("/+", "/");
					handlerMapping.put(url,method);
					controllerMap.put(url,clazz.newInstance());
					System.out.println(url+","+method);
				}
			}

		} catch (Exception e) {
			e.printStackTrace();
		}

	}

	/**
	 * Description:  将字符串中的首字母小写
	 * Params:
	 * @param name:
	 * return: java.lang.String
	 * Author: CXJ
	 * Date: 2018/6/16 19:13
	 */
	private String toLowerFirstWord(String name){

		char[] charArray = name.toCharArray();
		charArray[0] += 32;
		return String.valueOf(charArray);
	}

}